Electric working machine

ABSTRACT

The present invention provides an electric working machine in which a control board can be disposed without limitations based on a length of a brushless motor in a direction along an axial line. The electric working machine comprises: a brushless motor provided with a rotor and a stator; a motor case and a motor housing in which the brushless motor is stored; a control board which is provided outside of the motor housing in a radial direction of an axial line defined at the center of the rotor, and supports the switching elements; a connection board which is provided in the motor case, and supports the sensors; a through hole provided on the motor case; a through hole provided on the motor housing; and leads and signal lines extending from inside of the motor housing to the outside of the motor housing through the holes.

CROSS REFERENCE

This application is a continuation under 35 U.S.C. § 111(a) of U.S.patent application Ser. No. 15/505,597, filed on Feb. 21, 2017, which isthe U.S. National Phase under 35 U.S.C. § 371 of InternationalApplication No. PCT/JP2015/073537, filed on Aug. 21, 2015, and furtherclaims the benefit of Japanese Application No. 2014-176378, filed onAug. 29, 2014, the entire contents of each are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to an electric working machine which worksby transmitting a driving power of an electric motor to a tip tool.

BACKGROUND ART

Patent Document 1 has disclosed an electric working machine whichtransmits a driving power of an electric motor to a tip tool. Theelectric working machine described in Patent Document 1 comprises ahousing which has a motor housing, a gear case, and a handle housing.The handle housing is bent into an L-shape; a first end portion of thehandle housing is in contact with the motor housing, and a second endportion of the handle housing is in contact with the gear case. Abrushless motor is provided in the motor housing. The brushless motorhas a rotating shaft, a rotor, a stator, and a circuit board. The rotoris rotatable with the rotating shaft around a rotation axis. The circuitboard is provided with a Hall element which detects the rotationalposition of the rotor.

A board chamber is provided in the first end portion of the handlehousing, and a control board is provided in the board chamber. Switchingelements are mounted on the control board. A power cable connects coilsof the stator with the control board. Additionally, a communicationcable connects the Hall elements with the control board. A rotationalforce transmission mechanism and a planetary gear mechanism are providedin the gear case, the planetary gear mechanism being power-transmittablyconnected to a socket serving as the tip tool. The rotational forcetransmission mechanism is power-transmittably connected to the rotatingshaft.

RELATED ART DOCUMENT Patent Document

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2012-020363

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, in the electric working machine described in Patent Document 1,the control board is disposed in a position along the rotation axis ofthe electric motor. For this reason, arrangement positions of thecontrol board have limitations based on the length of the brushlessmotor in the direction along the rotation axis.

An object of the present invention is to provide an electric workingmachine in which the control board can be disposed without limitationscaused by the length of the electric motor in the direction along arotation axis.

Means for Solving the Problems

An electric working machine according to one aspect of the presentinvention comprises: an electric motor comprising a rotor and a stator;and a tubular housing in which the electric motor is stored, wherein theelectric working machine further comprises: a first control unit whichis provided outside of the tubular housing in a radial direction of arotation axis of the rotor, and which controls the electric motor; asecond control unit which is provided in the tubular housing, and whichcontrols the electric motor; a through hole on the tubular housingextending from the inside to the outside of the tubular housing; and anelectric wire which connects the first control unit with the secondcontrol unit, and extends into the hole.

Effects of the Invention

According to one aspect of the present invention, the first control unitis disposed on the outside of a tubular housing in a radial direction ofa rotation axial line defined at a center of the rotor. Therefore, thefirst control unit can be disposed without limitations caused by thelength of the electric motor in the direction along the rotation axialline.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional front view showing an electric workingmachine according to one embodiment of the present invention;

FIG. 2 is a block diagram showing a control circuit of the electricworking machine of FIG. 1;

FIG. 3 is an enlarged cross-sectional front view showing a main portionof the electric working machine of FIG. 1;

FIG. 4 is a perspective view showing a motor housing and a motor case ofFIG. 3 cut in a longitudinal direction;

FIG. 5 is a right-side cross-sectional view taken along a line V-V ofFIG. 3;

FIG. 6 is a cross-sectional view taken along a line VI-VI of FIG. 5;

FIG. 7 is a cross-sectional plan view taken along a line VII-VII of FIG.5; and

FIG. 8 is an enlarged cross-sectional front view showing a main portionof FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the embodiment of the present invention will be describedin detail on the basis of FIGS. 1 to 8. A tip tool 11 is detachablyattached to an electric working machine 10 which is also referred to asa “hammer drill”. The electric working machine 10 is utilized to carryout processes such as drilling concrete and stone material.

The electric working machine 10 has a working machine main body 12, inwhich a cylinder housing 13, an intermediate case 14, a handle 15, amotor housing 20 and a bottom cover 17 are fixed to each other. Thecylinder housing 13 is cylindrical in shape, and a cylinder 18 isprovided in the cylinder housing 13. The cylinder 18 is disposed on anaxial line A1 so as to be coaxial with a cylindrical tool holding member19. The tool holding member 19 is provided in the cylinder housing 13,and is rotatably supported by a bearing 16. The cylinder 18 and the toolholding member 19 are integrally rotatably connected to each other. Thetip tool 11 is attached to the tool holding member 19 so that arotational force of the cylinder 18 is transmitted to the tip tool 11.

An intermediate hammering element 21 made of metal is provided in thetool holding member 19 extending into the cylinder 18. The intermediatehammering element 21 is reciprocatively movable in a direction along theaxial line A1. A hammering element 22, which strikes the intermediatehammering element 21, is provided in the cylinder 18. The hammeringelement 22 is reciprocatively movable in the direction along the axialline A1. Additionally, a piston 23 is disposed in the cylinder 18, andis reciprocatively movable in the direction along the axial line A1. Anair chamber 24 is provided in the cylinder 18, between the hammeringelement 22 and the piston 23.

The intermediate case 14 is disposed between the handle 15 and thecylinder housing 13 in the direction along the axial line A1. The motorhousing 20 is fixed to both the cylinder housing 13 and the intermediatecase 14. An arrangement region of the motor housing 20 in the directionalong the axial line A1 partially overlaps an arrangement region of theintermediate case 14 in the direction along the axial line A1. Thehandle 15 is bent into an arch shape, and the two ends of the handle 15are attached to the intermediate case 14. A lever 132 and a power cable25 are attached to the handle 15. The handle 15 is also provided with anoperation switch 26. When the user operates the lever 132, the operationswitch 26 is turned ON or OFF.

The motor housing 20 is integrally molded and is made of conductivemetal such as aluminum. The motor housing 20 is tubular in shape, and amotor case 27 is disposed in the motor housing 20. The motor case 27 isintegrally molded and is made of insulating material such as syntheticresin. The motor case 27 has a tubular portion 27A as shown in FIG. 6,and the tubular portion 27A of the motor case 27 is press-fitted to themotor housing 20. The motor case 27 has a bottom portion 28 continuouslyconnected to the tubular portion 27A, and the bottom portion 28 isprovided with a shaft hole 29.

Furthermore, a brushless motor 30 is stored in the motor case 27. Thisbrushless motor 30 is a direct current motor, and has a tubular stator31 and a rotor 32 which is disposed in the stator 31. The rotor 32comprises an output shaft 33 and a rotor core 32 a which is fixed to theoutput shaft 33. In a front view of the electric working machine 10, anaxial line B1 defined as a rotational center of the output shaft 33intersects with the axial line A1 and, more specifically, is orthogonalto the axial line A1. The motor housing 20 is disposed between thebottom cover 17 and the intermediate case 14 in a direction along theaxial line B1. The motor housing 20 comprises a bearing support portion34 disposed on the bottom cover 17. A partition wall 35 is provided onthe intermediate case 14 and extends into the cylinder housing 13; theintermediate case 14 has a bearing 36 supported by the partition wall 35and a bearing 37 supported by the bearing support portion 34. The twobearings 36 and 37 are disposed at respective positions apart from eachother along the axial line B1 of the output shaft 33. The first end ofthe output shaft 33 is disposed in the shaft hole 29, and the second endof the output shaft 33 is disposed in the intermediate case 14. Theoutput shaft 33 has a portion which is partially disposed in theintermediate case 14, and a driver gear 38 is provided on the outerperiphery of this portion.

An insulator 39 is provided in the motor case 27. The insulator 39 isdisposed between the brushless motor 30 and the bearing 36 in thedirection along the axial line B1. As shown in FIG. 3, the insulator 39is provided with a shaft hole 40, and the output shaft 33 is disposed inthe shaft hole 40. The insulator 39 is made of synthetic resin, and isprovided in the motor case 27 so as to be fixed in the motor case 27.The insulator 39 is fixed to the stator 31.

A fan 41 is provided between the insulator 39 and the bearing 36 in themotor case 27. The fan 41 is fixed to and rotates with the output shaft33, thus functioning to induce air outside of the working machine mainbody 12 into the working machine main body 12. For this function, thebottom cover 17 is provided with a hole 17 a. The intermediate case 14has a portion extending in the same direction as the bottom cover 17,the portion being provided with a hole 14 a. The outside of the workingmachine main body 12 is communicated with the inside of the motor case27 through the shaft hole 29 and the hole 17 a. The outside of theworking machine main body 12 is communicated with the inside of theintermediate case 14 through the hole 14 a.

Hereinafter, a structure of the fan 41 which cools down the brushlessmotor 30 is described with reference to FIG. 3. The fan 41 is annular inshape, and is attached to the output shaft 33. In other words, the fan41 rotates with the output shaft 33. The fan 41 is a centrifugal fanwhich transports air from the inside outward in a radial direction ofthe axial line B1, and the fan 41 has a plurality of blades spaced in acircumferential direction. Air passages 42 are formed between theblades. The air passages 42 are disposed centered on the axial line B1in the radial direction, and extend from the inside outward; a suctioninlet 43 is disposed on the inner radial portion, and a dischargingoutlet 44 is disposed on the outer radial portion. The fan 41 is made ofnon-magnetic synthetic resin, and the fan 41 is attached with apermanent magnet 45 and a magnetic member 46.

The magnetic member 46 may be made of iron or steel and is molded into ashape of an annular plate which extends in the radial direction of thefan 41. The permanent magnet 45 is an annular member centered on theaxial line B1, in which north poles and south poles are alternatelydisposed along the circumferential direction of the permanent magnet 45.

A connection board 47 is provided in the motor case 27. The connectionboard 47 is fixed on, for example, the insulator 39. In other words, theconnection board 47 is attached to the stator 31 via the insulator 39.The connection board 47 is disposed between the stator 31 and thepermanent magnet 45 attached to the fan 41 in the direction along theaxial line B1. The connection board 47 is provided with a hole 48extending in a thickness direction of the connection board 47, and theoutput shaft 33 is disposed in the hole 48. The connection board 47 ismade of non-magnetic material such as synthetic resin, and magneticsensors S1 to S3 are mounted on the connection board 47. Additionally,the connection board 47 is provided with: a wiring to connect a coil U1with a lead 60, a wiring to connect a coil V1 with a lead 64, and awiring to connect a coil W1 with a lead 67. In the present invention, asecond control unit 131 includes the connection board 47 and themagnetic sensors S1 to S3 mounted on the connection board 47.

FIG. 2 is a block diagram showing a control circuit for controlling theelectric working machine 10. The brushless motor 30 utilizes acommercial power supply 49 as a power source, and the electric power ofthe commercial power supply 49 is applied to the coils of the brushlessmotor 30 through the power cable 25. A power indicator 50 is provided inthe intermediate case 14. The power indicator 50 lights up when thepower cable 25 is connected to the commercial power supply 49. Theelectric working machine 10 comprises a variable-speed switch 51 whichcan set a target rotational speed of the brushless motor 30. Thevariable-speed switch 51 has multiple stages, such as four stages, oftarget rotational speeds; when the variable-speed switch 51 is operated,the target rotational speed can be switched among the stages. Theelectric working machine 10 also comprises a speed display unit 52 fordisplaying the stage of the target rotational speed of the brushlessmotor 30.

Additionally, the stator 31 of the brushless motor 30 includes coils U1,V1 and W1 which respectively correspond to U-phase, V-phase and W-phase,and four permanent magnets 32 b which have opposite polarities arealternately disposed on a rotor core 32 a. The three magnetic sensors S1to S3 output detection signals indicative of a rotational position ofthe rotor 32. The three magnetic sensors S1 to S3 are respectivelyprovided for coils U1, V1 and W1 of the three phases. The magneticsensors S1 to S3 are non-contact sensors which respectively detect amagnetic force generated by the permanent magnet 45 attached to the fan41, and respectively convert the magnetic force into electric signals tobe transmitted. Hall elements may be utilized on the magnetic sensors S1to S3.

The electric working machine 10 has an inverter circuit 121 to controlcurrents to be respectively supplied to coils U1, V1 and W1. An electriccircuit between the commercial power supply 49 and the inverter circuit121 is provided with: a rectifier circuit 53 which rectifies analternate current of the commercial power supply 49 to a direct current,and a power factor correction circuit 54 which raises the voltage of therectified direct current and supplies the resulting voltage to theinverter circuit 121. The rectifier circuit 53 is constituted by diodeswhich are bridge-connected to each other. The power factor correctioncircuit 54 has an integrated circuit 56 which transmits a PWM controlsignal to a transistor 55 constituted by a field effect transistor orthe like; the power factor correction circuit 54 suppresses a harmoniccurrent generated by the switching elements in the inverter circuit 121to be equal to or smaller than the limit value. Furthermore, a noiseprevention circuit 57 is provided between the commercial power supply 49and the rectifier circuit 53, so as to prevent noise generated by theinverter circuit 121 from being transmitted to the commercial powersupply 49.

The inverter circuit 121 is a three-phase full-bridge inverter circuit,and has two switching elements Tr1 and Tr2 connected to each other, twoswitching elements Tr3 and Tr4 connected to each other, and twoswitching elements Tr5 and Tr6 connected to each other. The switchingelements Tr1 and Tr2 are connected in parallel with each other, and areconnected to a lead 58. A lead 60 is connected to the coil U1, and aconnector 59 connects the lead 58 with the lead 60.

The switching elements Tr3 and Tr4 are connected in parallel with eachother, and are connected to a lead 62. A lead 64 is connected to thecoil V1, and a connector 63 connects the lead 64 with the lead 62. Theswitching elements Tr5 and Tr6 are connected in parallel with eachother, and are connected to a lead 65. A lead 67 is connected to thecoil U1, and a connector 66 connects the lead 67 with the lead 65.

The switching elements Tr1, Tr3 and Tr5 are connected to an outputterminal on an anode side of the power factor correction circuit 54. Theswitching elements Tr2, Tr4 and Tr6 are connected to a terminal on acathode side of the power factor correction circuit 54 through a currentdetection resistor 122.

In this manner, the three switching elements Tr1, Tr3 and Tr5 connectedto the anode side of the power factor correction circuit 54 arepositioned on a high side of an electrical potential, and the threeswitching elements Tr2, Tr4 and Tr6 connected to the cathode side of thepower factor correction circuit 54 are positioned on a low side of theelectrical potential. The coils U1, V1 and W1 interconnect to form astar connection.

Moreover, the connection of the coils U1, V1 and W1 may be a deltaconnection. For example, when a control signal is transmitted to a gateof the switching element Tr1 on the high side and a gate of theswitching element Tr4 on the low side, electric currents are supplied tothe U-phase coil U1 and the V-phase coil V1. By controlling ON/OFFtiming and ON periods of the respective switching elements Tr1 to Tr6, acommutation for the coils U1, V1 and W1 are respectively controlled.

Control signals which control the inverter circuit 121 are computed andtransmitted by a motor control unit 133. The motor control unit 133comprises a controller 136, a control signal output circuit 134, a rotorposition detection circuit 135, a motor speed detection circuit 68, amotor current detection circuit 69, and an operation switch detectioncircuit 70. Detection signals of the magnetic sensors S1 to S3 aretransmitted to the rotor position detection circuit 135. The rotorposition detection circuit 135 detects the rotational position of therotor 32. The rotational position of the rotor 32 corresponds to apositional phase in the rotational direction of the rotor 32; therotational position of the rotor 32 has a positional relationship or anangle between a reference position in the rotational directionpredetermined by a fixed element, such as the stator 31, and a referenceposition determined by the rotational direction of the rotor 32.

The rotor position detection circuit 135 processes a signal indicativeof the rotational position of the rotor 32. A signal processed by therotor position detection circuit 135 is transmitted to the controller136 and the motor speed detection circuit 68. The motor speed detectioncircuit 68 detects a motor speed, and a signal provided from the motorspeed detection circuit 68 is transmitted to the controller 136.

The motor current detection circuit 69 is connected to both ends of thecurrent detection resistor 122, and detects a current flowing throughthe brushless motor 30. A signal provided from the motor currentdetection circuit 69 is transmitted to the controller 136. Thecontroller 136 has a microprocessor for processing control signals andmemory; the memory stores control programs, operation formulas, data,and the like. The controller 136 processes the signal transmitted fromthe motor speed detection circuit 68, and computes an actual rotationalspeed of the rotor 32. A signal processed by the controller 136 istransmitted to the control signal output circuit 134, and the invertercircuit 121 is controlled by a control signal transmitted from thecontrol signal output circuit 134.

In the present invention, a first control unit 130 is provided andincludes a control board 71; the motor control unit 133, the rectifiercircuit 53, the power factor correction circuit 54, the inverter circuit121, and the current detection resistor 122 are mounted on the controlboard 71. Wirings are mounted on the control board 71 to mutuallyconnect electric or electronic parts, such as the motor control unit133, the rectifier circuit 53, the power factor correction circuit 54,the inverter circuit 121, and the current detection resistor 122.

The control board 71 is disposed outside of the motor housing 20 andinside of the intermediate case 14. The control board 71 is disposedoutside of the motor housing 20 in the radial direction of the axialline B1. The control board 71 is disposed between the motor housing 20and the handle 15 in the direction along the axial line A1. Thethickness direction of the control board 71 is the same as the radialdirection of the axial line B1.

The control board 71 is integrally molded and is made of insulatingmaterial such as synthetic resin. An arrangement region of the controlboard 71 in the direction along the axial line B1 partially overlaps thearrangement region of the motor housing 20 in the direction along theaxial line B1. Additionally, signal lines 75 individually transmit thesignals of the magnetic sensors S1 to S3 to the rotor position detectioncircuit 135.

As shown in FIG. 5, a heat sink 78 is mounted on the control board 71and is in contact with the switching elements Tr1, Tr3 and Tr5. Thecontrol board 71 is further provided with: a heat sink 79 in contactwith the switching element Tr2, a heat sink 80 in contact with theswitching element Tr4, and a heat sink 81 in contact with the switchingelement Tr6. The heat sinks 79, 80 and 81 are mounted on the controlboard 71. Each heat sink 78 to 81 is integrally molded and is made ofthermo-conductive metals such as aluminum or copper, and by transferringthe heat of the switching elements Tr1 to Tr6 to air, the heat sinks 78to 81 cools the switching elements Tr1 to Tr6.

As shown in FIG. 3, the rectifier circuit 53 mounted on the controlboard 71 is disposed between the heat sink 78 and the bottom cover 17,in the direction along the axial line B1. When seen in a side view ofthe control board 71 as shown in FIG. 5, an arrangement region of therectifier circuit 53 partially overlaps the axial line B1. Moreover, asshown in FIG. 5, arrangement regions of the switching elements Tr1 toTr6 do not extend to the axial line B1. Furthermore, a lower surface 53a of the rectifier circuit 53 is flat, and the lower surface 53 a isinclined relative to the axial line B1. The lower surface 53 a isinclined toward the switching element Tr5.

In addition, a board case 82 is provided outside of the motor housing20. The control board 71 is attached to the board case 82. The boardcase 82 has a tray-shape and includes a bottom portion 83, and sidewalls 84 formed on the peripheral portion of the bottom portion 83. Theboard case 82 is integrally molded and is made of insulating materialsuch as synthetic resin. The control board 71 is disposed in a spacesurrounded by the side walls 84, and is in parallel with the bottomportion 83.

The bottom portion 83 is provided with a first tubular portion 85 and asecond tubular portion 86, in which the first tubular portion 85 extendsto the second tubular portion 86. The first tubular portion 85 protrudesfrom the bottom portion 83 toward the motor housing 20, and the secondtubular portion 86 protrudes in a direction opposite to a protrudingdirection of the first tubular portion 85. Additionally, as shown inFIGS. 3, 4 and 7, a passage 87 extends through the first tubular portion85 and the second tubular portion 86. The second tubular portion 86 isdisposed in the space surrounded by the side walls 84. As shown in FIG.8, the control board 71 is provided with a through hole 88 which extendsin the thickness direction, and the second tubular portion 86 isdisposed in the hole 88. An arrangement region of the connection board47 partially overlaps an arrangement region of the passage 87 in thedirection along the axial line B1.

The motor housing 20 is provided with a through hole 89, and the tubularportion 27A of the motor case 27 is provided with a through hole 90.Arrangement positions of the holes 89 and 90 partially overlap eachother in the direction along the axial line B1, and the arrangementpositions partially overlap in a circumferential direction of the axialline B1. Moreover, the first tubular portion 85 is disposed in the holes89 and 90. Therefore, the outside of the motor housing 20 iscommunicated with the inside of the motor case 27 by the passage 87.Furthermore, the leads 60, 64 and 67 and the signal lines 75 aredisposed through the passage 87.

Additionally, a circuit board 91 is provided in the intermediate case14, and a variable-speed switch 51 and an LED lamp 92 are mounted on thecircuit board 91. The LED lamp 92 is disposed on the rear surface of thespeed display unit 52. The circuit board 91 is disposed in a moreoutward position than the board case 82 in the radial direction of theaxial line B1. An electric wire 93 connects the circuit board 91 withthe control board 71. The intermediate case 14 has an opened windowportion 95, and the window portion 95 is covered by a cover 96. Thecover 96 is integrally molded and is made of transparent syntheticresin. A speed switch button 97 is attached to the cover 96, and whenthe user operates the speed switch button 97, the variable-speed switch51 is operated so that a target rotational speed is switched. Thecircuit board 91 is held in the intermediate case 14 by a circuit boardholder 98.

Arrangement regions of the circuit board holder 98 and the circuit board91 partially overlap arrangement regions of the output shaft 33 and thecontrol board 71 in the direction along the axial line B1. Additionally,arrangement regions of the circuit board holder 98 and the circuit board91 are disposed between a vibration damping mechanism 124 and theswitching elements Tr1 to Tr6 in the direction along the axial line B1.

As shown in FIG. 8, the tubular portion 27A has a thick portion 99 and athin portion 100 which are disposed at locations different from eachother in the direction along the axial line B1. The thick portion 99 andthe thin portion 100 are disposed between the hole 90 and an opening end101 of the tubular portion 27A in the direction along the axial line B1.Moreover, the thin portion 100 is disposed between the thick portion 99and the opening end 101 in the direction along the axial line B1. Thethick portion 99 and the thin portion 100 are molded into annular shapesand are provided over an entire periphery of the tubular portion 27A,and the thick portion 99 is thicker than the thin portion 100 in theradial direction of the axial line B1. An inner peripheral surface 100 aof the thin portion 100 and an inner peripheral surface 99 a of thethick portion 99 are mutually connected by a step surface 102.

The fan 41 has an outer peripheral surface, and a flange 103 is providedover the entire peripheral surface. The flange 103 is provided within anarrangement region of the thin portion 100 in the direction along theaxial line B1. An outer diameter of the flange 103 is less than an innerdiameter of the thin portion 100, and is greater than an inner diameterof the thick portion 99. Additionally, the fan 41 is provided with a rib104 which extends from an end face of the flange 103 toward theconnection board 47 in the direction along the axial line B1. The rib104 is molded into an annular shape centered on the axial line B1, andan outer diameter of the rib 104 is less than the inner diameter of thethick portion 99. The rib 104 has a tip in the direction along the axialline B1, and the tip is disposed in the thick portion 99 in the radialdirection of the axial line B1. In addition, the thick portion 99 andthe thin portion 100 form a minor gap 105 along with the flange 103 andthe rib 104. The minor gap 105 has a crank-like shape along a planewhich includes the axial line B1.

The following describes a power conversion mechanism 120 in which arotational force of the output shaft 33 in the brushless motor 30 isconverted into a reciprocating operation force of the piston 23. Acrankshaft 106 is rotatably provided in the intermediate case 14. Thecrankshaft 106 is in parallel with the output shaft 33, and a drivengear 107 provided on the crankshaft 106 is meshed with the driver gear38. A crank pin 108 is eccentrically attached to the crankshaft 106.

Moreover, a connecting rod 109 power-transmittably connects the crankpin 108 with the piston 23. Thus, when the rotational force of theoutput shaft 33 is transmitted to the crankshaft 106 so that the crankpin 108 is revolved, the piston 23 is reciprocatively moved in thecylinder 18. The power conversion mechanism 120 includes the crankshaft106, the crank pin 108, and the connecting rod 109.

The following describes a mechanism in which the rotational force of theoutput shaft 33 is converted into the rotational force of the cylinder18. The rotational force transmitting shaft 110 is rotatably provided inthe cylinder housing 13, and a driven gear 111 is provided in therotational force transmitting shaft 110. The driven gear 111 is meshedwith a driver gear 112 of the crankshaft 106. The rotational forcetransmitting shaft 110 is rotatably supported by bearings 113 and 114.Therefore, the rotational force of the output shaft 33 is transmitted tothe rotational force transmitting shaft 110 through the crankshaft 106.Additionally, a bevel gear 115 is attached to the rotational forcetransmitting shaft 110.

On the other hand, a cylindrical bevel gear 116 is disposed on an outerperiphery of the cylinder 18, and the bevel gear 116 is rotatable aboutthe cylinder 18. The bevel gear 116 is meshed with the bevel gear 115. Asleeve 117, which is integrally rotated with the cylinder 18 and ismovable in the direction along the axial line A1, is disposed on theouter periphery of the cylinder 18. The electric working machine 10 isprovided with a mode switching dial 123, and when the user operates themode switching dial 123, the sleeve 117 moves in the direction along theaxial line A1. Moreover, a clutch mechanism engages the sleeve 117 withthe bevel gear 116, or releases them from each other.

When the sleeve 117 moves along the axial line A1 relative to thecylinder 18, the sleeve 117 is either power-transmittably engaged withthe bevel gear 116, or is released from the bevel gear 116. When thesleeve 117 is engaged with the bevel gear 116, a rotational force of therotational force transmitting shaft 110 is transmitted to the bevel gear116. In contrast, when the sleeve 117 is released from the bevel gear116, no rotational force of the rotational force transmitting shaft 110is transmitted to the cylinder 18.

Inside the intermediate case 14, the vibration damping mechanism 124 isprovided between the power conversion mechanism 120 and the handle 15 inthe direction along the axial line A1. The vibration damping mechanism124 is provided with a weight 126, and the weight 126 swings with asupport shaft 125 serving as a fulcrum. The weight 126 swings within apredetermined angle range along a plane direction of the axes A1 and B1.An arrangement region of the vibration damping mechanism 124 partiallyoverlaps an arrangement region of the brushless motor 30 and thearrangement region of the control board 71 in the direction along theaxial line A1.

The following describes a usage example for the above-mentioned electricworking machine 10. When the user operates the lever 132 so that theoperation switch 26 is turned ON or OFF, an ON or OFF signal processedby the operation switch detection circuit 70 is transmitted to thecontroller 136. When the ON signal is transmitted to the controller 136,the control signal output circuit 134 processes a control signal whichis transmitted to the inverter circuit 121, and the switching elementsTr1 to Tr6 are individually turned ON and OFF so that the currentssuccessively flow through the respective coils U1, Y1 and W1. Then thecoils U1, Y1 and W1 and the permanent magnets 32 b cooperate with eachother to generate a rotating magnetic field to rotate the rotor 32 ofthe brushless motor 30.

The controller 136 executes controls in which the actual rotationalspeed of the rotor 32 approaches the target rotational speed. The actualrotational speed of the rotor 32 is controlled by adjusting voltageswhich are applied to the respective coils U1, V1 and W1. Morespecifically, the control is executed by adjusting a duty ratio of theON signals which are respectively applied to gates of the switchingelement Tr1 to Tr6 in the inverter circuit 121.

When the rotor 32 of the brushless motor 30 rotates, the powerconversion mechanism 120 converts the rotational force of the outputshaft 33 into the reciprocating operation force of the piston 23 so thatthe piston 23 is reciprocatively moved in the cylinder 18.

When the piston 23 is moved in a direction toward the crankshaft 106,the pressure of the air chamber 24 is lowered, and the hammering element22 moves away from the intermediate hammering element 21. When thehammering element 22 moves away from the intermediate hammering element21, air is unable to be drawn into the air chamber 24. After the piston23 reaches a top dead center, the piston 23 moves from the top deadcenter toward a bottom dead center; thus pressure in the air chamber 24rises. The hammering element 22 then strikes the intermediate hammeringelement 21. A striking force applied to the intermediate hammeringelement 21 is then transmitted to a target through the tip tool 11. Thehammering element 22 reciprocatively moves in the cylinder 18 while theoutput shaft 33 of the brushless motor 30 is rotating; thus thehammering element 22 intermittently strikes the intermediate hammeringelement 21.

When the reciprocating movements of the piston 23 and the intermittentstriking of the intermediate hammering element 21 on to the hammeringelement 22 cause the working machine main body 12 to vibrate in thedirection along the axial line A1, the weight 126 swings with thesupport shaft 125 serving as a fulcrum; thus the vibration of theworking machine main body 12 is reduced.

On the other hand, the rotational force of the output shaft 33 of thebrushless motor 30 is transmitted to the rotational force transmittingshaft 110 through the driver gear 112. When the mode switching dial 123is operated to select a hammer-and-rotate mode, the rotational force ofthe rotational force transmitting shaft 110 is transmitted to thecylinder 18, and the cylinder 18 is rotated. The rotational force of thecylinder 18 is transmitted to the tip tool 11 through the tool holdingmember 19. In this manner, the electric working machine 10 transmits thestriking force and the rotational force to the tip tool 11. In contrast,when the mode switching dial 123 is operated to select a hammer mode, norotational force of the rotational force transmitting shaft 110 istransmitted to the cylinder 18.

Moreover, the fan 41 rotates when the output shaft 33 of the brushlessmotor 30 rotates so that air outside of the working machine main body 12can flow through the hole 17 a and the shaft hole 29, and then can bedrawn into the motor case 27. The heat of the brushless motor 30 is thentransmitted into air so that the brushless motor 30 is cooled. Moreover,the air outside of the motor housing 20 is induced into the intermediatecase 14 through the hole 14 a. Therefore, the heat of the rectifiercircuit 53 and the switching elements Tr1 to Tr6 are transmitted to air.Thus, the temperature of the rectifier circuit 53 and the switchingelements Tr1 to Tr6 is suppressed from rising.

Since the air induced into the intermediate case 14 is directed to movein a direction along the lower surface 53 a of the rectifier circuit 53,the amount of air to be made in contact with the switching elements Tr1to Tr6 is increased to its maximum; thus, the switching elements Tr1 toTr6 can be efficiently cooled. The air which removed the heat from therectifier circuit 53 and the switching elements Tr1 to Tr6 then flowsthrough the passage 87 and is induced into the motor case 27. The airdrawn into the motor case 27 by the rotation of the fan 41 is theninduced through air passages 42 into the intermediate case 14. The airis finally discharged through a passage (not shown) to the outside ofthe working machine main body 12.

The control board 71 in the electric working machine 10 of the presentembodiment is disposed outside of the motor housing 20 in the radialdirection of the axial line B1 of the output shaft 33. Therefore, thecontrol board 71 can be disposed without being subjected to thelimitation of the brushless motor 30, in particular, the limitationbased on the length direction of the output shaft 33. Moreover, theworking machine main body 12 can be prevented from growing in size inthe direction along the axial line B1.

Furthermore, the outer diameter of the flange 103 of the fan 41 islarger than the inner diameter of the thick portion 99. Additionally,the thick portion 99 and the thin portion 100 form a minor gap 105 alongwith the flange 103 and the rib 104. The minor gap 105 has a crank-likeshape and acts as a labyrinth seal. Therefore, the air is made to flowinward so that the air, which was discharged outward from thedischarging outlet 44 by the centrifugal force of the fan 41, can flowthrough the minor gap 105. That is, a direction of the air flow isreversed, and the kinetic energy of air is reduced by a flow resistance;thus, the air discharged from the discharging outlet 44 can be preventedfrom returning to the arrangement region of the connection board 47.

As a result, an air flow, in which the air in the intermediate case 14flows through the passage 87 into the motor case 27, can be preventedfrom blockages. The air which cooled down the control board 71 in theintermediate case 14 is thus prevented from stagnating in theintermediate case 14. Therefore, a cooling performance of the controlboard 71 can be prevented from decreasing.

Moreover, since the control board 71 is set in the direction along theaxial line B1, the air induced into the intermediate case 14 from thehole 14 a can then flow in the direction along the axial line B1.Therefore, the flow of air which had cooled down the control board 71can be prevented of blockages.

Furthermore, the motor housing 20 is made of aluminum and disposed so asto protrude from the cylinder housing 13 in the direction along theaxial line B1. Therefore, the strength of the motor housing 20 issecured so that when the electric working machine 10 is utilized and themotor housing 20 is made in contact with an object, the motor housing 20can be prevented of deformation. Additionally, when vibrations caused bythe reciprocating movements of the piston 23 and the striking movementsof the hammering element 22 to the intermediate hammering element 21 aretransmitted to the working machine main body 12, the motor housing 20deflects against the cylinder housing 13, thus suppressing the vibrationof the working machine main body 12.

Moreover, the arrangement region of the control board 71 partiallyoverlaps the arrangement region of the vibration damping mechanism 124in the direction along the axial line A1. For this reason, when thecontrol board 71 is disposed outside of the motor housing 20, anarrangement region for the sole purpose of setting the control board 71does not need to be provided, and the electric working machine 10 can beprevented from growing in size in the direction along the axial line A1.Furthermore, a region is secured in the direction along the axial lineA1 in the intermediate case 14, in which the weight 126 is allowed toswing. A portion of an arrangement region of the first control unit 130in the direction along the axial line A1 partially overlaps a portion ofa swinging region for the weight 126. Therefore, the electric workingmachine 10 is prevented from growing further in size in the directionalong the axial line A1.

In addition, the noise prevention circuit 57 is provided in the handle15, and the first control unit 130 is disposed in a dead space formedbetween the brushless motor 30 and the noise prevention circuit 57 inthe direction along the axial line A1. Therefore, the electric workingmachine 10 is further prevented from growing in size in the directionalong the axial line A1.

The following describe correspondence between a structure of the presentembodiment and a structure of the present invention: the brushless motor30 corresponds to an electric motor of the present invention, theworking machine main body 12 corresponds to a working machine main bodyof the present invention, the rotor 32 corresponds to a rotor of thepresent invention, and the stator 31 corresponds to a stator of thepresent invention. Moreover, the axial line B1 corresponds to a rotationaxis of the present invention, and the motor housing 20 and the motorcase 27 correspond to a tubular housing of the present invention.Furthermore, the first control unit 130 corresponds to a first controlunit of the present invention.

The magnetic sensors S1 to S3 correspond to rotational positiondetection sensors of the present invention, and the second control unit131 corresponds to a second control unit of the present invention. Theleads 58, 60, 62, 64, 65 and 67 and the signal lines 75 correspond toelectric wires of the present invention. The coils U1, V1 and W1correspond to coils of the present invention, the permanent magnets 32 bcorresponds to permanent magnets of the present invention, and the fan41 corresponds to a fan of the present invention. The control board 71corresponds to a control board of the present invention, and theconnection board 47 corresponds to the supporting board of the presentinvention. The magnetic member 46 corresponds to a magnetic member ofthe present invention, the bottom cover 17 and the bottom portion 28correspond to a bottom portion of the present invention, and the hole 17a and the shaft hole 29 correspond to ventilation holes of the presentinvention.

Additionally, the shaft hole 29 corresponds to a first hole of thepresent invention, and the hole 17 a corresponds to a second hole of thepresent invention. The motor housing 20 corresponds to an outer housingof the present invention, and the motor case 27 corresponds to an innerhousing of the present invention. The board case 82 corresponds to aholder of the present invention, and the first tubular portion 85 andthe second tubular portion 86 correspond to tubular portion of thepresent invention. Additionally, the holes 89 and 90 correspond to holesof the present invention; the hole 90 corresponds to a first hole of thepresent invention, and the hole 89 corresponds to a second hole of thepresent invention. The thick portion 99, the thin portion 100 and theflange 103 correspond to a regulating mechanism of the presentinvention.

Furthermore, the piston 23 corresponds to an operation member of thepresent invention, and the axial line A1 corresponds to an operationcenter line of the present invention, the power conversion mechanism 120corresponds to a power convertor of the present invention, the tip tool11 corresponds to a tip tool of the present invention, and the hammeringelement 22 corresponds to a hammering element of the present invention.

The present invention is not limited to the above-mentioned embodiment,and can be variously modified without departing from the scope of theinvention. For example, the electric working machine of the embodimenthas a configuration in which power is supplied to the brushless motorfrom the commercial power supply, that is, an alternate current powersupply. However, the electric working machine of the present inventionincludes an electric working machine in which a battery pack, serving asa direct current power supply, is attached to the working machine mainbody, and power of the battery pack is supplied to the brushless motor.The electric working machine of the present invention is any machine inwhich the tip tool is operated by a power of the electric motor.

The electric working machine of the present invention includes astructure in which the inverter circuit 121 is mounted on the connectionboard 47. The electric working machine of this structure is providedwith electric wires which connect the inverter circuit 121 with thepower factor correction circuit 54, and extend into the passage 87.Moreover, the wirings provided on the control board 71 or the connectionboard 47 include leads, printed circuits and printed wirings.

The electric working machine of the present invention includes a hammerdrill and a hammer driver which apply a rotational force and a hammeringforce to the tip tool in the radial direction. The electric workingmachine of the present invention includes an impact driver and an impactdrill which apply a rotational force and an impact force to the tip toolin a rotational direction. Moreover, the electric working machine of thepresent invention includes a driver, a drill, a grinder, and a sanderwhich apply only the rotational force to the tip tool. The electricworking machine of the present invention includes a hammer and a nailerwhich apply only the hammering force in the radial direction to the tiptool. The electric working machine of the present invention includes ajigsaw and a saber saw which reciprocatively move the tip tool. Theelectric wires of the present invention include leads through whichelectric currents flow and signal lines through which electric signalspass. The leads and signal lines have conductors coated by syntheticresin or rubber-like elastic bodies.

LIST OF REFERENCE SIGNS

10: electric working machine

11: tip tool

12: working machine main body

17: bottom cover

17 a: hole

18: piston

20: motor housing

22: hammering element

27: motor case

28: bottom portion

29: shaft hole

30: brushless motor

31: stator

32: rotor

32 b: permanent magnets

41: fan

46: magnetic member

47: connection board

53: rectifier circuit

54: power factor correction circuit

58, 60, 62, 64, 65 and 67: leads

71: control board

75: signal lines

82: board case

85: first tubular portion

86: second tubular portion

89 and 90: holes

99: thick portion

100: thin portion

103: flange

120: power conversion mechanism

121: inverter circuit

130: first control unit

131: second control unit

133: motor control unit

134: control signal output circuit

A1 and B1: axial lines

S1 to S3: magnetic sensors

U1, V1 and W1: coils

1. An electric working machine comprising: a motor including an outputshaft; a motor case having a cylindrical shape extending in parallelwith a first axis of the output shaft, the motor case accommodating themotor, the motor case comprising a side wall surrounding the motor and abottom disposed at one end of the side wall; a first control unitcomprising first circuit elements to control the motor, the firstcontrol unit being disposed outside the side wall of the motor case; asecond control unit comprising second circuit elements to control themotor, the second control unit being disposed inside the side wall ofthe motor case; a fan disposed inside the side wall of the motor case,the fan rotating when the output shaft is driven; a housing at leastpartially covering the motor case; and an electric path connecting thefirst circuit elements with the second circuit elements, wherein themotor case has a first opening in the bottom and a second opening in theside wall, wherein the electric path passes through the second opening,and wherein the electric working machine has a first air path connectingoutside of the housing and inside of the motor case through the firstopening, and a second air path connecting outside of the housing andinside of the motor case through the second opening.
 2. The electricworking machine according to claim 1, further comprising a first bearingand a second bearing that support the output shaft, wherein the outputshaft runs through the first bearing, the motor, and the second bearingin that order, and wherein the first bearing, the second opening, andthe second bearing are arranged in that order along a first directionparallel with the first axis.
 3. The electric working machine accordingto claim 2, wherein the first bearing, the first and second controlunits, and the second bearing are arranged in that order along the firstdirection.
 4. The electric working machine according to claim 2, whereinthe first opening surrounds the second bearing.
 5. The electric workingmachine according to claim 1, wherein the second control unit comprisinga circuit board on which the second circuit elements are disposed, thecircuit board having a first surface and a second surface, the firstsurface and the second surface crossing the first axis, the firstsurface is closer to the first control unit than the second surface,wherein the electric path including wiring that runs from the firstsurface of the circuit board to the first control unit.
 6. The electricworking machine according to claim 1, wherein the housing has a thirdopening, wherein the second air path connects outside of the housing andinside of the motor case through the third opening, and wherein thefirst control unit is disposed in the second air path.
 7. The electricworking machine according to claim 1, further comprising: a tip tool;and a hammering element that delivers striking force to the tip toolalong a second axis crossing the first axis.
 8. The electric workingmachine according to claim 7, wherein the tip tool, the motor, and thefirst control unit are arranged in that order along a second directionparallel with the second axis.
 9. An electric working machinecomprising: a motor including an output shaft; a motor case having acylindrical shape extending in parallel with a first axis of the outputshaft, the motor case accommodating the motor, the motor case comprisinga side wall surrounding the motor and a bottom disposed at one end ofthe side wall; a first control unit comprising first circuit elements tocontrol the motor, the first control unit being disposed outside theside wall of the motor case; a second control unit comprising secondcircuit elements to control the motor, the second control unit beingdisposed inside the side wall of the motor case; a fan disposed insidethe side wall of the motor case, the fan rotating when the output shaftis driven; a housing at least partially covering the motor case; a firstbearing and a second bearing that support the output shaft, the outputshaft running through the first bearing, the motor, and the secondbearing in that order; and an electric path connecting the first circuitelements with the second circuit elements, wherein the motor case has afirst opening in the bottom and a second opening in the side wall,wherein the electric path passes through the second opening, and whereinthe first bearing, the second opening, and the second bearing arearranged in that order along a first direction parallel with the firstaxis.
 10. The electric working machine according to claim 9, furthercomprising: a tip tool; and a hammering element that delivers strikingforce to the tip tool along a second axis crossing the first axis. 11.The electric working machine according to claim 10, wherein the tiptool, the motor, and the first control unit are arranged in that orderalong a second direction parallel with the second axis.